Get self closing tag through xpath in xml file in c#

Can you please tell me how to get this

my code: var varSearchTerm2 = from x in xDocFile.XPath2SelectElements("//xref[not(node())][not(@*)]") select x;`

Input :

<xref/>
<xref></xref>
<xref></xref>

my output look like this:

<xref/>